Here's mine:
git remote --verbose | grep origin | grep fetch | cut -f2 | cut -d' ' -f1
no better than the others, but I made it a bash function so I can drop in the remote name if it isn't origin.
grurl () {
xx_remote=$1
[ -z "$xx_remote" ] && xx_remote=origin
git remote --verbose | grep "$1" | grep fetch | cut -f2 | cut -d' ' -f1
unset xx_remote
}